Exopolysaccharide production by Propionibacterium acidi-propionici on milkmicrofiltrate

Aims: The aims of this work were to evaluate growth and exopolysaccharide ( EPS) production properties of Propionibacterium acidi-propionici DSM 4900 o n milk permeate. Methods and Results: Anaerobic growth on milk permeate was only possible if supplemented with yeast extract (YE). Fermentation capacities of the strai n were significantly improved by further increasing the supplemented YE. At 5 g 1(-1) YE, consumption of 45 g 1(-1) lactose to produce 9 g 1(-1) bioma ss, 34 g 1(-1) organic acids and 0.65 g l(-1) EPS was observed. From a kine tic point of view, EPS production occurred during the bacteria growth phase . At the excreted polysaccharide level, the medium showed shear-thinning be haviour with a relatively high apparent viscosity of up to 30 mPa.s (milli. Pascal.second) at a shear rate of 17 s(-1) Conclusions: EPS production by P. acidi-propionici DSM 4900 on milk permeat e showed promising rheological behaviour of the milk-derived medium obtaine d, even at a low production level. Significance and Impact of the Study: A kinetic study on EPS production by a food-grade bacterium that could be used in situ in alimentation was carri ed out.